Spring base for seat cushions



June-4, 1957 j. s. PLATT 2,794,493

, SPRING BASE FOR SEAT cushion; Filed Dee. 21, 1255s 7 2 ants-sheet 1'INVENITOR. Jai 61 flaff 7 United States atent G SPRING BASE FOR SEATCUSHIONS John G. Platt, Carthage, Mo., assiguor to 'Flex-O-Lators, Inc.,Carthage, Mo., a corporation of Missouri Application December 21, 1955,Serial No. 554,531

2 Claims. (Cl. 155179) This invention relates to new and usefulimprovements in furniture Seating, and relates more particularly to thespring bases for seat cushions.

The principle object of the present invention is the provision of aspring base for seat cushions having novel means whereby the relativesoftness or firmness of the cushion may be varied adjustably to suit thepreference of the individual user.

' Another object is the provision of a spring base of the characterdescribed wherein the relative yieldability of different portions of thesame cushion may be adjusted.

A further object is the provision of a spring base of the characterdescribed wherein the adjustment of the firmness of the springs isaccomplished substantially without variation of the normal tension ofthe springs, whereby to avoid the overloading, permanent setting-andfatigue of the springs which might otherwise result from theadjustments. These objects are accomplished by supporting the cushion bymeans of cantilever type springs fixed in the seatframe and extendinggenerally parallel to the cushion surface, and by providing rigidsupports beneath said springs at an adjustably variable distance fromthe fixed ends thereof.

Other objects are simplicity and economy of construction, efficiency anddependability of operation, and adaptability of the spring structureinvolved to be applied to pre-existing types of seating with a minimumof alteration thereof.

With these objects in view, as well as other objects which will appearin the course of the specification, reference will be had to thedrawing, wherein:

Fig. l is a top plan view of a spring base for a chair embodying thepresent invention, with the upholstery layers omitted, being a sectionalview taken on line I--I of Fig. 2, and

Figs. 2 and 3 are sectional views taken respectively on lines II-II andIII-III of Fig. 1.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies to the main frame of a chair, shownfragmentarily and including front corner uprights 4 and 6, rear corneruprights 8 and 10, side rail 12 interconnecting and fixed to corneruprights 4 and 8, side rail 14 interconnecting and fixed to corneruprights 6 and 10, and a horizontal back rail 16 interconnecting andfixed to rear corner uprights 8 and 10. Said frame carries afloor-engaging leg 18 at each corner thereof. The back and armstructures of the chair, not shown, may be carried by the corneruprights, but form no part of the present invention.

The seat frame 20 is substantially rectangular in form, comprising afront rail 22 extending between and detachably secured at its oppositeends to front uprights 4 and 6 by bolts 24, a rear rail'26 extendingbetween and detachably secured at its opposite ends to rear uprights 8and 10 by bolts 28, and a pair of parallel side rails 27 and 29extending between said front and rear rails and aflixed thereto inspaced apart relation. It will be understood that the specificconstruction of the main frame and seat frame as shown are exemplaryonly, except those structural features thereof used and useful in thesupport and adjustment of the spring elements hereinafter described.

Seat frame 20 carries a plurality of generally planar spring units 30disposed in vertical planes extending from front to rear of the seat andspaced regularly across the width of the seat. Each of said spring unitscomprises a single length of spring wire having a horizontal reach 32disposed above and parallel to the plane of seat frame 20, inwardly anddownwardly sloping reaches 34 and 36 connected at their upper ends tothe ends of reach 32'by bends 38, outwardly extending horizontal reaches40 and 42 connected at their inner ends to reaches 34 and 36 by bends44, the extreme outer end portions of each of reaches 40 and 42 beingreceived in a transverse slot 46 formed in the upper edge of front rail22 or rear rail 26, as the case may be, and being bent downwardly asindicated at 48 to fit into a vertical socket 50 drilled in said rail.The insertion of the spring ends into sockets 50 prevents the springunits from tilting laterally out of their planes, and the disposition ofreaches 40 and 42 in rail slots 46 prevents the spring ends 48 frompivoting in sockets 50. Said spring ends are secured against rising outof said sockets by a pair of bars 52 and 54 laid re-.

spectively along the upper edges of rails 22 and 26 and secured theretoby screws 56.

The central horizontal reaches 32 of the spring units form thesupporting surface for the padding and upholstery layers (not shown),said upholstery layers having their edges drawn downwardly and tacked orotherwise suitably secured to the seat frame rails. Reaches 32 arejoined together by a pair of cross Wires 58 and 60 disposed respectivelyat the forward and rearward ends of reaches 32 andextending transverselythereto. Said cross wires are joined to each of the spring units by asuitable clip 62. It will be seen that the end portions of said crosswires are bent into the vertical planes of the outer most spring units30 for connection thereto, and that the bend portions 38 of theintermediate spring units are bent into the vertical planes of the crosswires for connection thereto. It will of course be understood thatadditional cross wires could be added intermediate wires 58 and 60 ifneeded.

It will be seen that each of the reaches 40 and 42 of the spring unitsconstitutes a cantilever spring fixed at one end in the seat frame, andhaving a free end at the bend 44. Reaches 40 and 42 are alsoapproximately parallel to the seating surface of the cushion and arepreferably so installed that this parallelism will occur after whateverpre-stressing of the springs is caused by the installation of thepadding and upholstery. The cantilever springs 40, which are disposedalong the front edge of the seat and afiixed in front rail 22, aresupported by a horizontal bar 64 extending transversely thereto andparallel to front rail 22, and cantilever springs 42 are supported by ahorizontal bar 66 extending transversely thereto and parallel to rearrail 26. Each of the springs is supported in a groove 68 formedtransversely in the upper edge of the associated support bar. The bottomof each of said grooves is formed arcuately in the plane of the springunit, in order to support the spring smoothly regardless of the flexureof the spring reach supported therein as best shown in Fig. 2. Each endof each of the support bars 64 and 66 is provided with a tongue 70 (Fig.3), said tongues being slidably carried in a pair of grooves 72 formedrespectively in the inner faces of side rails 27 and 29 of the seatframe.

It will thus be seen that support bars 64 and 66 may be moved adjustablyalong the length of the cantilever springs 40 and 42 supported thereby,and will vary the '3 effective lengths thereof. The effective length. ofthe cantilever springs, for practical purposes, is the length thereofbetween the support bar and the free end of the spring- (at bend 4 lThus when: the: support barslare; moved inwardly so as. to be disposedat or 'adjacentbends 44, as. in Fig. 2, the cantileverspi'ings '40 and'iwillhave; a-minimumeifective l'engtha'nd hence a. maximumijdegfee' of,stiffness, and the seat will have its maximum degree of firmness.Conversely, when thesupport bars- Q64 and 66 aremoved relativelyoutwardly toward front and rear rails 22 and 26, the effective lengthandLyieldabiIity of cantilever springs 40 and 42'arefincreased', and theseat will be-relatively soft and yieldable. It is also apparent thatsupport has, 64' and 66 may be adjusted'independ ently, so that therelativeyieldability of the front and rear portions of the sear may beadjusted to the users preference. The adjustment is rapid, and easy,since the bars 64 and 66'are easily accessible fromthe bottom of thechair. g 7

It is of course true that even with the support bars positioned directlybeneath bends 44, and thence with the seat having its maximum degree ofhardness, the spring reaches 34 and 36 still'provide some yieldability.However, the: adjustability is provided substantially entirely byvarying the effective lengths of the spring reaches 40' and 42, andtheyieldability of reaches 34 and 36 is con- I sidered of minorimportance in this inventiomand they could be of dilferent degrees ofrigidity without affecting the. main concepts involved. In fact, insofaras certain of the broader concepts involved are concerned, the portionsof the spring units above bends 44 may be considered as mere supportingsuperstructure which could be of nearly any design. This generalization,however, does not 'apply to the features of the spring structure whichprovide substantially independent support for the front and rear edgesof the seat. I

It is also considered important that the adjustment of the yieldabilityof the cushion is accomplished substantially without varying the normaltension of the spring units. This eliminates to a large degree anyoverloading of the springs, or any permanent deformation or fatiguingthereof, which. might occur if the adjustment were accomplished byvarying the spring tension.

While I have shown and described 'a specific embodiment of my invention,it will be apparent that many minor changes of structure and operationcould be made without departing from the spirit of the invention asdefined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

l. A spring base for seat cushions, said base comprise...

ing a rigid seat frame, aplurality of spring units each comprising a,length of spring wire and disposed in a vertical plane extending fromfront to rear of said frame, each of said units having a central portiondisposed generally horizontally above said frame, generally horizontalend portions extending horizontally forwardly and rearwardly in theplane of said frame and secured at their extreme ends'in said frame, andangled. portions connecting said end portions to said central portion,the central portions of all of said units forming a cushion supportingsurface, and a pair of support members carried by said frame, one ofsaid support members engaging and supporting the forward end portions ofall of said spring.

units, and the other of said support members engaging and supporting therearward end portions of all of said spring units, said support members.being movable horizontally in said frame whereby to. engage said springunits at variable distances from the fixed ends thereof:

2. The structure as recited in claim lwherei'n said frame includes. siderails parallel to the planes of said spring units, and wherein saidsupport members comprise a pair of bars extending transversely beneathsaid springs and each having its 'ends'disposed slidably in a pair ofhorizontal grooves formed respectively in the confronting faces of saidside rails.

References Cited in the file of; this patent UNITED STATES PATENTSGibbons Apr. '20; 1948

